Electronic fuel injection (EFI) is a fuel supply system that directly injects a specific amount of fuel into the cylinder or intake manifold using injectors. The injection quantity is determined by the energization duration of the injector's solenoid coil (i.e., the injection pulse width). The ECU, based on sensor signals, precisely controls the injection quantity by controlling the injector's opening time and injection timing.
A high-pressure common rail system mainly consists of a high-pressure fuel pump, a common rail, and electronically controlled injectors. Based on control signals from the ECU, the electronically controlled injectors control the opening and closing of solenoid valves, injecting fuel from the high-pressure rail into the combustion chamber at a set injection timing, quantity, and rate. The injection pressure can reach over 2000 bar, and it can perform multiple injections, including pre-injection and main injection.
Piezoelectric injectors utilize the piezoelectric effect to achieve rapid and precise control of the needle valve. Their response speed is faster than traditional solenoid valve injectors, and they have lower triggering energy consumption and higher control accuracy.
Composite injection technology combines intake manifold injection and cylinder direct injection, switching or working in tandem under different operating conditions such as engine cold start, low load, and high load.